Single-tracer, dual-phase Tc-MIBI parathyroid scintigraphy is based on the differential washout rate of the tracer (MIBI) from the thyroid and the parathyroid tissue. A distinct focus of increased MIBI uptake relative to the thyroid gland, either on the early or late image or on both, or a focal uptake in the mediastinum, is considered positive for abnormal parathyroid tissue. Tc99m-MIBI planar scintigraphy was found to play a major role in the preoperative localization of a parathyroid adenoma (PTA), with a sensitivity ranging from 85% to 95% and specificity of up to 99%. Subsequently, the use of MIBI- Single photon emission computed tomography (SPECT) significantly improved the sensitivity of the test and improved the accuracy of lesion localization.